Method of pretreating metal surfaces

ABSTRACT

A steel surface pre-treated with an oily material and a phosphating agent in which the surface is (a) first coated with up to 50 milligrams phosphating agent per square meter of surface, and then the oily material is coated on the surface; or (b) the phosphating agent and oily material are simultaneously coated on the surface to provide up to 50 milligrams of phosphating agent per square meter of surface and at least 150 milligrams of oily material per meter of surface; or (c) the phosphating agent and oily material are simultaneously coated on the surface to provide up to 150 milligrams of oily material per square meter of surface.

Unite States atet [191 Evans et al.

METHOD OF PRETREATING IVIETAL SURFACES Inventors: Albert Edward John Evans,

Lovendean; Anthony Norbert Aincough, Ropley, both of England; Koen Verschoore, Essen, Belgium Assignee: Koninklijke Emballage Industrie Van Leer B.V., Amstelveen,

Netherlands Filed: Oct. 24, 1972 Appl. No.2 300,303

Foreign Application Priority Data Oct. 22, 1971 Netherlands 7114590 US. Cl l48/6.l5 R; 117/134; 252/387;

' 106/14; I48/31.5 Int. Cl. C23c l/l0; C22b B23b 9/02 Field of Search 148/6.14, 6.15 R, 6.152,

References Cited UNITED STATES PATENTS 8/1970 Smith et a1 148/6152 FOREIGN PATENTS OR APPLICATIONS 625,297 6/1949 United Kingdom Primary Examiner-John D. Welsh Attorney, Agent, or Firm--Fleit & Jacobson [5 7] ABSTRACT A steel surface pre-treated with an oily material and a phosphating agent in which the surface is (a) first coated with up to 50 milligrams phosphating agent per square meter of surface, and then the oily material is coated on the surface; or (b) the phosphating agent and oily material are simultaneously coated on the surface to provide up to 50 milligrams of phosphating agent per square meter of surface and at least 150 milligrams of oily material per meter of surface; or (c) the phosphating agent and oily material are simultaneously coated on the surface to provide up to 150 milligrams of oily material per square meter of surface.

27 Claims, No Drawings METHOD OF PRETREATING METAL SURFACES The present invention relates to a method of pretreating metal surfaces, by applying a protecting layer thereon, with the object of enhancing the performance of organic coatings and/or preventing early rusting. The metal particularly subjected to said treatment is steel.

A serious problem in steel drum production is that the surface of steel coils or sheets received from the steel mills frequently shows contamination, particularly in the form of rust patches, often as speckled rust. Some extra treatments are required to render the steel surface to a condition suitable for coating, without introducing adverse effects, e.g. water-sensitivity. Time and money would be saved if the steel mills were able to deliver steel substantially free from rust and other undesirable contaminants, having a temporary rust resistance, yet remaining a suitable substrate for coating without extra treatments.

It is generally known that rusting of steel can be prevented by applying an oily substance to the surface or by phosphating the surface and it is also known that phosphating the surface and sealing the phosphate e.g. by means of an oil, is practised,

With regard to preventing steel from rusting, said systems can meet practical requirements, but a common disadvantage is that steel protected by such an oil or oil sealed phosphate cannot be coated without degreasing, as the application and performance of many coatings would be impaired, whilst protection by phosphating alone at the levels used to achieve rust resistance and coating performance is uneconomic or impracticable for general use. Said disadvantage causes serious troubles in the manufacture of steel drums which have to be coated with paint externally and often lacquered internally. Steel being prevented from rusting according to said known methods can rarely be satisfactorily coated without having removed said oil, if applied. Consequently, the steel-drum manufacturer has to de grease the steel surface with organic solvents, such as trichloroethylene, or wash the steel surface with alkaline aqueous solutions, e.g. aqueous solutions of sodium hydroxide, sodium carbonate, alkali metal silicates or condensed phosphate, particularly pyrophosphates, or with acidic aqueous solutions, e.g. aqueous solutions of mono alkali metal phosphate. According to British patent specification 625.297 the wearing properties and storage life of metal surfaces may be improved by applying a stabilized solution, paste or emulsion containing orthophosphoric acid and a water insol uble non-drying polar oil or fat in a weight ratio of from 1 100 till 100. Though the proportion of protec tive material per m is not stated, it appears that such an amount of polar oil or fat, particularly degras must be applied, that a finishing coat may be applied only after having removed said oily material without removing the phosphate film.

Further U.S. Pat. specification No. 3.525.651 discloses a one step process for applying an aqueous zinc phosphate solution, containing a solid particulate mixture of a fatty lubricant and a water soluble surface active agent. If the material treated has to be subjected to a deforming operation, the coating applied will provide sufficient lubrication, but if it has to be subjected to a severe deforming operation, a lubricant film may be applied to the coated metal surfaces. As would be anticipated and as the applicants have shown, oil films very much lighter than those used for the protection of steel do not as such give adequate protection against atmospheric rusting; phosphate coatings very much lighter than those used as pretreatments for painting also do not give adequate rust protection. But. surprisingly, it was found that adequate rust resistance and coating performance were achieved in a superior way by applying the phosphating agent and the oily material simultaneously or separately, but excluding systems wherein more than 50 mg/m phosphating agent are deposited in a separate step directly on the metal or in combination with more than 150 mg/m oily material. Also it was found that the method described hereinafter allows to obtain a surprisingly high degree of lubricity, together with superior rust resistance and even of benefit, at least without harm to the performance of coatings which are eventually subsequently applied without prior degreasing. 1n the present application the term oily material" indicates oils that are not water-soluble and small amounts of which easily dissolve in the solvents commonly used in paint or glue systems. These include: mineral oils, vegetable oils, animal oils and other fatty oils, synthetic oils, modified oils and planticizing oils. The selection of the specific material depends on the application.

The components may be applied as a mixture of an oily material and a phosphating agent or separately for instance by a treatment of the steel surface with an oily material followed by a further treatment with a phosphating agent.

The oily material and the phosphating agent may be applied as an emulsion or as a solution (it is essential that an appreciable amount of water is present during the treatment to facilitate the ionisation of the phosphating agent). Preferably the oily material and the phosphating agent are applied as an emulsion. Such as emulsion may be prepared e.g. from dilute phosphoric acid, a surfactant and dioctylsebacate.

Dioctylsebacate, which is used frequently in the manufacture of tinplate, is the preferred oily material.

The preferred phosphating agent is ortho-phosphoric acid, but other phosphoric acids, phosphorus oxy acid or acid phosphating formulations (eventually combined with detergents) are not excluded.

The preferred concentration will vary depending on a number of parameters, e.g. substrate, treatment time and temperature, method of application and required performance, but will often be in the range of 0.01 to 1.0% by volume aqueous solution. The amount of phosphate applied per m may be considerably lower than the amount of phosphate generally applied according to prior art.

The presently described process preferably produces a phosphate layer of 0.01 50 mg per m It is however not excluded to carry out the process in such a way that phosphate is not measurable or in a way that phosphate layers of greater thickness are obtained. If the phosphating agent contains an accelerator, e.g. sodium nitrate, sodium nitrite, sodium chlorate, copper or nickel salts, an improved phosphate layer is formed, whilst the temperature and time required to form said layer are reduced. The same can be achieved if a phosphating accelerator is present on the steel surface to be protected. The preferred accelerator is a combination of sodium nitrite and sodium nitrate. Though the amount of oily material to be applied is not limited. amounts of 5- mg of oily material per m are preferred. de-

pending on such parameters as mentioned hereabove. It may be appropriate to use an excess of protecting agent, eg an aqueous emulsion of the oily material and the phosphating agent. in order to nullify the adverse effects of contaminants, if any. present. Thus the usual cleaning treatment given to steel prior to painting may be omitted partially or wholly. It may be desired to create surface conditions. particularly controlled lubricity. which then allow metal working operations. such as drawing, to be performed on the steel sheet as received. This can be achieved according to the process described hereabove by the selection of a suitable oily material. The emulsion or solution of the components. as well as both components separately, may be applied to the steel according to various methods. such as rolling, dipping, brushing, spraying. Only a short contact time with the treating solution or emulsion is required. but this is not a restrictive feature. Preferably a contact time of less than 3 minutes, particularly less than 30 seconds is used. A short drying time after the application is recommended. The present process may be used for treating cold reduced steel as well as pickled, hot rolled steel. The treatment may be carried out during any processing step subsequent to annealing (or pickling when necessary) in the manufacture of cold or hot rolled steel. The present process is of particular importance in the manufacture of steel strip, particularly that used in the manufacture of steel drums. Steel treated according to the invention has to be packaged in the usual way. Generally, steel stacks and coils are enveloped with a polyethylene paper laminate which, in turn, is enveloped by a steel sheet outer casing, eventually supported by timber battens. thereby preventing the direct impingement of the atmospheric elements. Thus, by treating steel surfaces in accordance with the present invention, surface conditions are created resulting in (i) a superior degree of rust resistance, (ii) an excellent appearance over a considerable period of time, (iii) enhancement of the performance of subsequently applied organic coatings, and (iv) a favourable degree of lubricity.

The following examples are given to illustrate the in vention, without thereby limiting the scope of the invention to the specific details of the examples.

The test methods used in the undermentioned examples ll8 are as follows:

I. PAINTABILITY a. General Paint is spray applied to the steel panels I50 X 300mm or 150 X 100mm) which are held vertically in front of a waterfall-type spray booth.

A Brillant Green pigmented paint was used in all cases except where otherwise indicated. The spray unit used is a conventional hand spray gun and the paint is applied in a conventional way to a thickness of mm in one coat. A 5 minute flashoff period in a dust free atmosphere is allowed prior to stoving.

After the panel has been removed from the oven and allowed to cool the paint thickness is established using an electromagnetic induction gaugev A suitable number of such panels are used to provide eighteen 55mm di ameter disc specimens for the range of tests to be carried out as described below.

The specimens are conditioned by exposure to the following environments.

i. Ambient atmospheric temperature and humidity.

ii. \Vater soaking at 4t) '3 02C in an agitated. thermostatically controlled. heated water bath for a spe cific time.

b. Reverse Impact Testing (1.5mm Indentation) The method used for this test is based on BS3900: Part E3: 1966 (Impact). the apparatus conforming to the specification. and the method of assessment of the results being slightly modified. I

The assessment of the result of applying a 2.5 mm reverse impact indentation to the specimen is made as follows:

A strip of 25mm wide transparent pressure sensitive tape is applied over the indented paint surface and pressed in order that it adheres to the paint. The tape is then snatch-peeled from the paint. removing all non adherent paint film. The resultant strip of tape is then applied to millimetre squared paper for permanent recording of the result and for measurement of area of paint film removed. The measurement is achieved by estimating the diameter of the disc of paint removed. In instances where the disc is not all paint but consists of tiny flakes the area of paint removed is still taken to be the area of the disc.

Three specimens are evaluated for each substrate. coating and conditioning and the average area of paint removed is recorded.

Since control treatments and substrates are included in a test programme, a baseline value is obtained for the performance of each coating/substrate combination. Areas are expressed in square millimetres. and it is recognized that variations of 20 30mm representing i 2mm in diameter, are within experimental variation and do not represent significant changes in performance. Larger differences between the baseline and any modifications reflect changes in performance either in improvement or deterioration.

In cases where the tape pull removes paint film from isolated areas of the undeformed part of the test specimen as well as on the indented area, the result is recorded as severe loss of adhesion (SLA). In the extreme case where the paint is removed from the whole or nearly the whole of the test specimen the result is recorded as complete loss of adhesion (CLA). Results 01 CLA or SLA represent far more serious failures than results expressed numerically as an area removed, be cause of the adhesion loss from undeformed areas.

ERICHSEN DRAW:- DIN 53156 BS. 3900 Part E4, 1969 (cupping) The method and apparatus are based on BS 390C Part E4, 1969 (cupping) for single depth of indentation with modified interpretation of the results, and include the use of 16, 18 or 20 BO. steel sheet, as steel mill finished or polished, and testing carried out under ambient conditions.

The method of assessment of the 7.0mm cupping test on the specimens is as for the Reverse Impact except that instead of measuring the area removed a system 01 graduated loss of adhesion is employed, ranging frorr zero to complete in 8 steps (see reference table I (page 1 1 Again 3 specimens are tested after each conditioning and the resultant grades averaged (the last 2 grades n01 being figures warrant separate mention).

In interpreting the results a difference of 2 or more grades compared to the control value is significant. Dif- 5 ferences of one grade can be due to experimental variation. As in the interpretation of the reverse impact results the recording of SLA or C LA. indicates a far more serious failure.

RUST RESISTANCE Resistance to rusting is assessed comparatively, results being related to the amount of rust developed according to the system shown in reference table ll (page 12).

All data presented are the mean of 3 sample panels 140mm X 74mm subjected to 85 90 percent relative humidity at i 1C.

FIG. 2 is the standard chart for microscopic and. macroscopic examination of corrosion according to Champion (Corrosion Testing Procedures, F. A. Champion, second Edition 1964, pp 203 205). The relationship between descriptive number, standard term and number of rust spots per sq.dm. is given in Table A. The size of individual rust spots observed, was always 8 mm (assessed by the method according to Champion).

Reference table I Characterisation of standard erichsen draw test result grade O idealised specimen no visible loss of adhesion or cracks only visible description t isolated spots or very small flakes removed.

- i spots or very small flakes approximating a ring or disc removed spots or very small flakes removed.

large solid flakes approximating a disc removed.

Reference table l'-Continued Characterisation of standard erichsen draw test result grade description idealised specimen 1) no visible loss of adhesion or cracks only visible S.L.A, SEVERE LOSS OF ADHESlON OTHER THAN AT THE STRESS POINT C.L.A. COMPLETE LOSS OF ADHESION. OR NEARLY SO Reference table 11 modorcle number very law considerable number law numerous small number VQFY numerous Table A Descripthc .\uml-t standard Term Number per st 'LlIll Few Small Numlw Number 5 L'ot;-itlcrable mumber Numerom \'er Numerous lln? F ll

llvtLll Luau- PHOSPHATE CONCENTRATION ON THE; STEEL SURFACE steel panels after drying were established by Geiger Muller scintillation counting.

The quantities of phosphoric acid (phosphate) which were found on the surface of the steel dipped for :0 seconds in the 0,05 percent phosphoric acid solution are given below. The vaiues quoted below are given in mg H;,PO /m"'.

The coating on the steel panels were as follows:

Phosphoric Acid (90% w/w) 0.05 '7: (v/v) Concentration Time of Dip (sec.)

Coating on surface Trichloroethylene degreased steel Steel with 50 mg/nf" sodium Nitrite Steel with 15 mg/m" I dioctyl sehacate Steel with [00 mg/m dioctyl sehacate Steel with 50 mg/m" Sodium nitrite and sebacate 5 Steel with 50 mg/m" Sodium nitrite and I00 mg/m" dioctyl sebacatc H PO coating weights in mg/m" EXAMPLE I An emulsion was prepared containing 1 percent /v) dioctyl sebacate, 0.1 percent (/v) ortho-phosphoric acid (90 percent "/w),0.2 percent ('lv) sodium nitrate, 0. 11 percent ("/v) sodium nitrate and 0.05% (/v) Triton X-45 surfactant in water. Cold reduced mild steel panels (supplied according to BS. 1449, Part 18, 1962, (R4 quality. roughness nominally 60 micro inches) were dipped in this emulsion for 10 seconds, drained, and dried stood vertically for l hour at ambient temperature. 47 mg/m of dioctyl sebacate were found to be deposited on the steel surface.

These steel panels were subjected to the paintability and rusting resistance tests detailed above and the following results were obtained:

(a) Paintability Trichloroethylene Steel treated Conditions Test degreased steel as above Reverse Impact 55mm'- removed 100mm Ambient removed Erichsen grade 3 grade 3 Reverse Impact SLA mm removed I day water soak Erichsen grade 5/Sl .A grade 4 (h Rust Resistance percent ("/v) triethanolamine and 0.05 percent (/v) Pluronic L64 surfactant was prepared. Cold reduced, mild steel panels were dipped in this solution for 10 seconds and allowed to drain and dry at ambient temperature. These steel panels were shown to have SOmg/m of sodium nitrite deposited on their surface. An emulsion containing 1 percent ("/v) dioctyl sebacate, O.l percent ("/v) orthophosphoric acid percent)'/w,0.05 percent ("/v) Triton X-45 in water was prepared. The sodium nitrite coated steel panels were dipped into the emulsion for l0 seconds, drained and dried stood vertically for 1 hour at ambient temperatures. l08mg/m of dioctyl sebacate were found to be deposited on the steel surface.

These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained:

(a) Paintabilit Steel treated as above Reverse Impact 55mm removed 60mm removed -Continued (a) Paintability (a) Paintability Triehloroethylene Steel treated Triehloroethylene Steel treated Conditions Test degreased steel as above Conditions Test dcgreased steel as above Ambient 2 2 Erichsen grade 3 grade 1 Ambient Reverse Impact 55mm remmed 90mm removed t 7 2 l d W, tar Reverse Impact SLA cfimm removed Erichsen grade 3 grade 3 Reverse Impact SLA 50mm removed i 4 w I I day Enchsen Gmdb SISLA grade 4 water soak Erichsen grade S/SLA grade 4 (b) Rust Resistance Triehloroethylene Steel treated Conditions degreased steel as above Immediate I I 24 hours at 85-90% RH 2 l 7 days at EXAMPLE 3 An emulsion containing 1 percent /v) linseed oil, 0.1 percent ("/v) orthophosphoric acid (90 percent)'/w and 0.05 percent ("/v) Triton X45 in water was prepared. Cold reduced mild steel panels were dipped into the emulsion for 10 seconds, drained and dried stood vertically for I hour at ambient temperature. 84mg/m of linseed oil were found to be deposited on the steel surface.

These steel panels were subjected to the paintability and rust resistance tests detailed above and the follow ing results were obtained:

(a) Paintability Triehloroethylene Steel treated Conditions test degreased steel as above Reverse Impact 55mm removed 25mm removed Ambient Erichsen grade 3 grade I Reverse Impact SLA mm" removed 1 day water soak Erichsen grade 5/SLA grade I (b) Rust Resistance Triehloroethylene Steel treated Conditions degreased steel as above Immediate l I 24 hours at 85-90% RH 2 I 7 days at 85-90% RH 5 1 EXAMPLE 4 An emulsion containing 1 percent ("/v) dioctyl sebacate, 0.01 percent orthophosphoric acid (90 percent)/w and 0.05 percent ("/v) Triton X-45 in water was prepared. Cold reduced mild steel panels were dipped into the emulsion for 10 seconds, drained and dried stood vertically for 1 hour at ambient temperature. 43mg/m of dioctyl sebacate were found to be deposited on the steel surface.

. These steel panels were subjected to the palntability and rust resistance tests detailed above and the following results were obtained:

(b) Rust Resistance Triehloroethylene Steel treated Conditions degreased steel as above Immediate l l 24 hours at -90% RH 2 l 7 days at 85-9071 RH 5 I EXAMPLE 5 An emulsion containing 1 percent ("/v) dioctyl sebacate, 1 percent ("/v) orthophosphoric acid percent)"'/w and 0.05 percent ("/v) Triton X-45 in water was prepared. Cold reduced mild steel panels were dipped into the emulsion for I0 seconds, drained and dried stood vertically for 1 hour at ambient temperature. 97mg/m ofdioctyl sebacate were found to be deposited on the steel surface. These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained:

(a) Paintability Triehloroethylene Steel treated Conditions Test degreased steel as above Reverse Impact 55mm removed 40mm removed Ambient Erichsen grade 3 grade 1 Reverse Impact SLA 35mm'- removed 1 day water soak Erichsen grade S/SLA grade2 (b) Rust Resistance Triehloroethylene Steel treated Conditions degreased steel as above Immediate I l 24 hours at 85-90% RH 2 l 7 days at 85-90% RH 5 1 EXAMPLE 6 (a) Paintahility Trichloroethylene Steel treated Conditions Test degrcased steel as above Reverse Impact 55mm removed 60mm removed Ambient Erichsen grade 3 grade I Reverse Impact SLA 50mnf" removed 1 day water soak Erichsen grade S/SLA grade 3 (b) Rust Resistance Trichloroethylene Steel treated Conditions degreased steel as above Immediate l 2 24 hours at 85-90% RH 2 2 7 days at 85-9071 RH 2 EXAMPLE 7 An emulsion containing 1 percent ("/v) dioctyl sebacate, 0.1 percent ("/v) ortho-phosphoric acid (90 percent "/w) and 0.05 percent ("/v) Triton X-45 in water was prepared. Hot-rolled and oiled steel panels were trichloroethylene degreased and were then dipped into the emulsion for l0 seconds, drained and dried stood vertically for 1 hour at ambient temperature. l56mg/m of dioctyl sebacate were found to be deposited on the steel surface. These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained:

(a) Paintahility Trichloroethylene Steel treated Conditions Test degreased steel as above Reverse Impact 90mm" removed mm" removed Ambient Erichsen grade 2 grade 2 Reverse Impact C LA 30mm removed 1 day water soak Erichsen CLA grade 3 (b) Rust Resistance Trichloroethylene Steel treated Conditions degreased steel as above Immediate l l 24 hours at 85-90% RH l l 7 days at 85-90% RH l 1 EXAMPLE 8 An emulsion containing 0.025 percent (/v) dioctyl sebacate, 0.1 percent ("/v) ortho-phosphoric acid (90 percent '/w) and 0.05 percent Triton X- in water was prepared. Cold reduced mild steel panels were brushed with the emulsion to a visually uniform liquid level. The panels were drained and dried stood vertically for I hour at ambient temperature 54mg/m of dioctyl sebacate were found to be deposited on the steel surface.

. These steel panels were subjected to the paintabllity and rust resistance tests detailed above and the following results were obtained:

l a Palntability Steel treated as above 'l richloroeth lens Conditions Test degreased Steel Reverse Impact 55mm removed 95mm removed Ambient Erichsen Reverse Impact grade 3 SLA grade 5 35mm removed 1 day water soak Erichsen grade 5/51 .A grade 5 (b) Rust Resistance Trichloroethylene Steel treated Conditions degreased steel as above Immediate I I 24 hours at -90% RH 2 l 7 days at 85-90% RH 5 l EXAMPLE 9 An emulsion containing 0.25 percent ("/v castor oil, 0.1 percent ("/v) orthophosphoric acid percent'/w) and 0.05 percent"/v Triton X-45 in water was prepared. Cold reduced mild steel panels were dipped in the emulsion for 10 seconds, drained and dried stood vertically for 1 hour at ambient temperature. I 12 mg/m of castor oil were found to be deposited on the steel surface.

These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained.

(a) Paintability EXAMPLE 10 An emulsion containing 0.25 percent ("/v) lubricating oil (Croda fluid G 6938). 0.1 percent ("/v) orthophosphoric acid (90 percent'/w) and 0.05 percent ("/v) Triton X-45 in water was prepared. Cold reduced mild steel panels were dipped in the emulsion for 10 seconds. drained and dried stood vertically for 1 hour at ambient temperature. mg/m of the oil were found to be deposited on the steel surface. These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained:

EXAMPLE 1 1 An emulsion containing 0.25 percent ("/v) epoxidized linseed oil, 0.1 percent ("/v) orthophosphoric acid (90 percent"'/w) and 0.05 percent (WV) Triton X-45 in water was prepared. Cold reduced mild steel panels were dipped in the emulsion for seconds, drained and dried stood vertically for 1 hour at ambient temperatures. 6lmg/m of epoxidised linseed oil were found to be deposited on the steel surface.

These steel panels were subjected to the paintability and rust resistance tests detailedabove and the following results were obtained.

(a) Paintability Trichloroethylene degreased steel Steel treated Conditions Test as above Reverse Impact 55mm removed SOmm' removed Ambient Erichsen grade 3 grade I Reverse Impact SLA 55mm removed 1 day water soak Erichsen grade S/SLA grade 3 b) Rust Resistance EXAMPLE 12 An emulsion containing 1 percent /v) dioctyl sebacate, 0.1 percent ("/v) orthophosphoric acid (90 percent"'/w) and 0.05 percent ("/v.) Triton X-45 in water was prepared. Cold reduced mild steel panels were flooded with the emulsion and then passed through a nip roller. The time between the flooding and the passing of the panel through the nip roller was 10 seconds. The panels were stood horizontally and allowed to dry for 1 hour at ambient temperature. lO8mg/m of dioctyl sebacate were found to be deposited on the steel surface.

The steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained.

(a) Paintability Trichloroethylene Steel treated Conditions Test degreased steel as above Reverse Impact 55mm removed 55mm removed I day Ambient Erichsen grade 3 grade 2 Reverse Impact SLA 50mm removed 1 soak Erichsen grade 5/SLA grade 4 (b) Rust Resistance Trichloroethylene Steel treated Conditions degreased steel as above Immediate l l 24 hours at 8S90'/? RH 2 l 7 days at -90% RH S 2 EXAMPLE 1 3 a. A solution of 0.1 percent ("/v) orthophosphoric acid percent"'/w) and 0.05 percent ("/v) Triton X-45 in water was prepared; Cold reduced mild steel panels were flooded with the solution and then passed through a nip roller. The time between the flooding and the passing of the panel through the nip roller was 10 seconds. The panels were stood horizontally and allowed to dry for l hour at ambient temperature.

b. An emulsion containing 1 percent /v dioctylsebacate and 0,05 percent /v Triton X-45 was also prepared. Cold reduced mild steel panels were dipped into this emulsion for 10 seconds. drained and dried and stood vertically for 1 hour at ambient temperature. 61 mg per m of dioctylsebacate were found to be deposited.

These steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained:

(a) Paintability Conditions Steel treated according to item a) Steel treated according to item h 'l'richlorouthylene Test degreased steel Ambient Continued (at) Pillllltlhlill} Steel treated Steel treated 'l'richloroetlrvlcnc according In according to (onditions lest degreased steel item at item h) lirichsen grade 3 gradt i Reverse Impact Si A Mlmm rt-mm ed (LA' I l tIZI\ ater sunk lzi'ithscn grade Sl./\ gradt 4 ('l 1 lb) Rust Resistance Steel treated Stet-l treated l'richlorueth lcnc according to let-cording to Conditions degruased steel item a) item bl Immediate I I l l 7 7 7 24 hours at '7 V 7 7 85-00"; RH 2 l l 7 da \s at 85-00; RH 5 o I t (I i-mpleztloss of adhesion EXAMPLE 14 a. PAINTABILITY The surface of cold reduced mild steel panels were pro-coated with an oil (289 mg/m" of dioctyl sebacate containing 2.5 percent of Triton X-45 surfactant). The steel panels were flooded with a solution of 0.1 percent ("/v) orthophosphoric acid (90 percent"'/w) in water and then passed through a nip roller. The time between the flooding and the passing of the panel through the 30 nip roller was seconds. The panels were stood horizontally and allowed to dry for 1 hour at ambient temperature. The steel panels were subjected to the paintability and rust resistance tests detailed above and the following results were obtained: 35

(a) Paintahility Triehloroethylene Steel treated Conditions Test degreased steel as above Reverse Impact 55mm'-' removed 40mm removed 40 Ambient Erichsen grade 3 grade I Reverse Impact SLA 2()mm'-' removed 1 day water soak Erichscn grade S/SLA grade 4 (b) Rust Resistance 45 Trichloroethylene Steel treated Conditions degreased steel as above Immediate l I 24 hours at 50 85-90% RH 2 l 7 days at 85-9071 RH 5 1 EXAMPLE Cold reduced mild steel panels having a surface contaminated with 50-100 mg/m of dioctyl sebacatc percent ("'/w)), soluble inorganic salts. percent ("/w)), iron residues 13 percent ('/w)), smut and insoluble silica (2 percent ("'w)). triethanolamine (28 percent ("'/w)) and ethylene oxide-type surfactants 12 percent ("'/w)) were dipped in a 0.1 percent (/v) orthophosphoric acid (90 percent"'/w) solution for 10 seconds. stood vertically and allowed to drain and dry for 1 hour at ambient temperature.

These steel panels were subjected to the paintability, and rust resistance tests detailed above and the following results were obtained.

Contaminated steel Phosphoric acid treated Contaminated steel not Conditions Phosphoric acid treated Ambient 45mm removed 40mm removed I da watei" soak CLA 30mm removed 7 days water soak CLA 20mm removed (b) Rust Resistance Contaminated steel not Contaminated steel Conditions Phosphoric acid treated Phosphoric acid treated Immediate I I 24 hours at 85-909? RH I I 7 days at 85-90?! RH l EXAMPLE 16 An emulsion containing 1 percent ("/v) dioctyl sebacate, 0.l percent ("/v) orthophosphoric acid (90 percent"'/w) and 0.05 percent ("/v) Triton X- in water was prepared. The emulsion was sprayed onto cold reduced mild steel panels until a uniform liquid level was (a) Paintahilit 'l'richloroethflcne Steel treated Conditions lcst dcgrqascd steel as above Reverse Impact mm remmed 5llmm removed Ambient 7 Erichsen grade 3 grade I Reverse Impact SLA. 40mm removed 1 day water soak Erichsen grade 5/Sl..\ grade 4 -Continued Cold reduced mild steel panels (centre line average 60 micro inches) were dipped into the emulsion for 10 (a) Paintability seconds, drained and dried stood vertically for 1 hour v at ambient temperature. 83mg/m of dioctyl sebacate Tnchlmcthylcne Steel muted 5 were found to be deposited on the steel surface. (.OlldlllOnS Test degreased steel as above An emulsion containing 1 percent (/v) dloctyl seba- (b) Rusl Resismncc cate and 0,05 percent ("/v) Triton X-45 in water was Trichlomethflene Sled tremcd also prepared. Cold reduced miltll steel panels which Conditions degreased steel as above had been phos hated (50 mg/m r pp Into 1 I 1 this emulsion for 10 seconds, drained and dried stood 1 1 2. 2; vertically for 1 hour at ambient temperature. 42mg/m 85-90% RH 2 l of dioctylsebacate were found to be deposited on the 7 days at 85$); RH 5 2 phosphated steel panels. i I

These steel panels were sub ected to the palntability and rust resistance tests detailed above and the results, EXAMPLE 17 stated in tables C and D were obtained.

An emulsion containing 1 percent ("/v) dioctyl sebacate, 0.01 percent ("/v) orthophosphoric acid (90 percent lw) and 0.05 percent ("/v) Triton X-45 in water 20 was prepared. The emulsion was sprayed onto cold re- (a) Paintabilitv duced mild steel panels until a uniform liquid level was 7 d Th 1 I d th Tnchloroethylene attame e emu sion was a owe 0 remain on e degreused Steel panels for l0 seconds and then the panels were Coating Test (60 micro inches) wiped dry with a high pressure air jet. The panels Ambient were allowed to stand for 1 hour at ambient tempera- Reverse 2 impact 1 day w/s 55 ture. 58mg/m of dioctyl sebacate were found to be de Red Oxide 7 days MS 65 posited on the steel surface. These steel panels were Lacquer Ambient 2 subjected to the paintability and rust resistance tests Erichsen g y 3 Z! S t detailed above and the following results were obtained: y

TABLE C Plain steel dioctyl 'lrichloroethylene Phosphated steel dioctyl sehacate/phosphorie degreased steel 15-18 micro inches) sebacate emulsion dipped l5-l 8 micro inches) acid emulsion dipped (60 micro inches) 0 40 (l (l (15 20 0 75 l t) 4 2 t) 5 l l) 5 l (a) Paintability TABLE D Trichloroethylene Steel treated Conditions Test degreascd steel as above (b) Phosphated steel Plain steel dioctyl Reverse Impact 55 removed 65mm2 removed Conditions dioctyl sebacate sebacate phosphoric Ambient emulsion dipped acid emulsion dipped Erichsen grade 3 grade l Reverse Impact SLA 85mm removed Immediate l l 1 day 24 hours at water soak 85-90% RH l l 5 7 days at Erichsen grade /SLA grade 4 85A)?! RH l l (h) Rust Resistance EXAMPLE l8 An emulsion containing 1 percent (/v) dioctyl sebacate, 0.1 percent ("/v) orthophosphoric acid (88 percent) and 0.05 percent ("/v) Triton X-45 in water was prepared.

EXAMPLE l9 Panels were cut from a cold rolled, commercial quality, mild steel plate having a thickness of 1.25 mm.

Part of said panels were dipped for 5 seconds in a bath containing tap water, 0.02 percent Triton X-l00 and the respective percentages of acid stated in the table below. Then the panels were dried. Other panels were treated the same way but the treatment was followed by a dip for 5 seconds in a solution containing 5 g. Dioctylsebacate in l l. methylethylketone. The panels were then allowed to dry. This results in a -100 mg/m layer of dioctylsebacate. Still other panels have been treated first with Dioctylsebacate and afterwards with acids each in the way described above. Finally steel panels which received no treatment and panels dipped in the above mentioned Dioctylsebacate solution only, have been included for reference.

Panels were exposed outdoors under rainshield for 5 days, after which the percentage of rusted surface was determined visually. The results are given in the table:

taken from across the width of cold reduced mild steel strip, each set being trichloroethylene vapour degreased and treated as shown in the table below. Sets of samples were also included without any applied lubricant and with low density polyethylene film, thickness 100 um, applied to both sides.

RLTS'I' treatment no phosphating agent dioct \'lseliacate TREATMENT dioctvlsebacatc followed b followed h type gr/l dioct \lschacatc phosphating agent no acid lilo 91) H PO 85% 1 0o 20 3o POlyphoSphoric l 90 21) It) acid (8294 P. Phosphorous acid 309; 1 9o 30 2s Granodine 2U I J 30 95 5 1. Conditions according to instructions of supplier with 4 minutes diptime, at 90 C. Concentration of Steel Treatment Oil (mg/m") Some of the panels were subsequently coated with a Clean steel CrodafluidG6938 applied in excess layer of microns of a grey alkyd based paint. Tellus 15* on applied in excess 24 Hours after stoving the panels were immersed for Dioctylsebacate applied as a thin film from an 73 24 hours in distilled water having a temperature of C. Then the Erichsen 7.0 mm cupping test was carried out in order to determine the lacquer adhesion loss percentage.

By means of pressure sensitive tape poorly adhering paint, if any is removed and the adhesion loss determined as illustrated according to the method described in reference table I (page 1 1 The results are stated below.

In order to demonstrate the enhanced lubricating performance of the invention when applied to steel for use in metal forming, established methods of assessing lubricity, in both deep-drawing and stretch forming modes of deformation were used as described by:

J. C. WRIGHT (Sheet Metal Industries, 38, No. 414,

October 1961. p 731 741), D. H. LLOYD (Sheet Metal Industries, 39, No. 419,

March 1962, p 158 166),

J. F. WALLACE (The British Iron and Steel Research Association Report No. MW/E/62/55),

U.S. RAO (Sheet Metal Industries, 44, No. 486, Oc-

tober 1967, p 673 678). Steel discs 55mm in diameter were prepared in sets emulsion containing 1% v/v dioctylsebacate and 0.05% v/v Triton X-45.

Crodafluid 66938 applied as a thin film from an 21 emulsion containing (1.25% v/v Crodafluid C6938 and 0.0571 v/v Triton X-45 Tellus 15 oil applied as a thin film from an emulsion containing 1% v/v Tellus 15 oil and 0.0571 v/v Triton X-45.

Dioctylsehacate and orthophosphoric acid applied according to the invention from an emulsion containing 1'71 v/v dioctylsehacatc. 0.17: v/v orthophosphoric acid and 0.05% v/v Triton X-45 in water.

Crodafluid 06938 and orthophosphoric acid applied according to the invention from an emulsion containing 0.25% v/v Crodafluid 66938, (H /1 v/v orthophosphoric acid (90%) and 0.05% v/v Triton X-45 in water.

Tcllus 15 oil and orthophosphoric acid applied according to the invention from an emulsion containing 17! v/v Tellus 15 oil 0.19? v/v orthophosphoric acid (90%) and 0,05% v/v Triton X-45 in water,

Low density polyethylene [L m thick applied to each side of the disc.

Orthophosphoric acid treated by dipping in an aqueous solution of 0. 171 v/v orthophosphoric acid (90% Crodafluid @6938 obtained from Croda Chemicals Limited, *Tcllus 15 oil obtained from Shell-Mex and B.P, Limited.

The lubricating properties of these treatments were measured using an Erichsen W126 hydraulic testing machine equipped with means of measuring applied load and displacement data.

Stretch forming lubrication was assessed using Erichsen cupping tests on the 55mm diameter blanks, evaluation being by the depth of draw to failure and the maximum load applied. A large depth of draw and a low maximum load are indicative of efficient lubrication, the ideal being low density polyethylene film. Deep drawing lubrication was assessed using the Erichsen machine with the 33mm cup draw tools and 55mm diameter blanks. The relative lubricity of the various systems was evaluated in terms of the work done in achieving the draw and in terms of the peak drawing load. Low values of work done and peak load are indicative of efficient lubrication the ideal being low density polyethylene film.

The results obtained for the deep draw test are shown diagrammatically on the following page.

In all cases investigated the lubricating performance of the invention was superior to that of the components applied independently and was generaly superior to the 9. The method of claim 1' in which said surface is uniformly coated with 0.01 to 50 milligrams of said phos- DEEP DRAW TEST STEEL TREATMENT Maximum force applied (arbitrary units) Ill 20 60 NO LUBRICANT APPLIED (i) clean degreased steel 55 3 out of 4 specimens split (ii) phosphoric acid treated 38.0

CONVENTIONAL LUBRICATING OILS APPLIED IN EXCESS (i) Crodalluid 66938 In (ii) Tellus 15 law OILS APPLIED AS THIN FILMS FROM DILUTE AQUEOUS EMULSIONS (i) dioctylsebacate |34.l I

(ii) Crodafluid 66938 145.6 I out of three specimens split 1 (iii) Tellus 15 ps OILS APPLIED ACCORDING TO THE INVENTION (i) dioctylselmcate I335 I m ii) Crodafluid 06938 has 1 (iii) Tellus E0 1 EXAMPLE OF EXTREMELY GOOD LUBRICANT Polythene film I218 I I l 0 ll) 3O 5O 60 Maximum force applied (arbitrary units) 'spccimcnts) failed to dru and s lit under load.

What is claimed is:

l. A steel surface pre-treated to provide superior rust protection, high lubricity and direct paintability without degreasing, said surface having a first uniform coating of up to milligrams of phosphating agent per square meter of surface and a second uniform coating of an oily material selected from the group consisting of mineral oils, vegetable oils, animal oils and equivalent synthetic oils, said phosphating agent being coated on said surface from an acidic aqueous solution of said phosphating agent, said second coating being applied subsequent to said first coating.

2. The steel surface of claim 1 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.

3. The steel surface of claim 2 in which said phosphorus oxy acid is orthophosphoric acid.

4. The steel surface of claim 1 in which said oily material is dioctylsebacate.

5. The steel surface of claim 1 in which an accelerator is used to accelerate the coating of said phosphatin g agent on said surface.

6. The steel surface of claim 4 in which said accelerator is sodium nitrite or sodium nitrate.

7. The steel surface of claim 1 in which said acidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.

8. The method of claim 1 in which said surface is uniformly coated with about 5 to 100 milligrams of said oily material per square meter of surface.

phating agent per square meter of surface.

10. A steel surface pre-treated to provide superior rust protection, high lubricity and direct paintability without degreasing, said surface having a uniform coating of up to 50 milligrams of phosphating agent per square meter of surface and at least milligrams of oily material per square meter of surface, said phosphating agent and said oily material being coated on said surface simultaneously, said phosphating agent being coated on said surface from an acidic aqueous solution of said phosphating agent, said oily material being selected from the group consisting of mineral oils, vegetable oils, animal oils and equivalent synthetic oils.

1]. The steel surface of claim 10 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.

12. The steel surface of claim 11 in which said phosphorus oxy acid is orthophosphoric acid.

13. The steel surface of claim 10 in which said oily material is dioctylsebacate.

14. The steel surface of claim 10 in which an accelerator is used to accelerate the coating of said phosphating agent on said surface.

15. The steel surface of claim 14 in which said accelerator is sodium nitrite or sodium nitrate.

16. The steel surface of claim 10 in which said acidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.

17. The steel surface of claim 10 in which said oily material and said phosphating agent are located on said surface from an aqueous emulsion.

18. The steel surface of claim in which said surface is uniformly coated with 0.0l to 50 milligrams of said phosphating agent per square meter of surface.

19. A steel surface pre-treated to provide superior rust protection, high lubricity and direct paintability without degreasing, said surface being coated with a phosphating agent and up to 150 milligrams of oily material per square meter of surface, said phosphating agent and said oily material being coated on said surface simultaneously, said phosphating agent being coated on said surface from an acidic aqueous solution of said phosphating agent, said oily material being selected from the group consisting of mineral oils, vegetable oils. animal oils and equivalent synthetic oils.

20. The steel surface of claim 19 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.

21. The steel surface of claim 20 in which said phosi 24 phorus oxy acid is orthophosphoric acid.

22. The steel surface of claim 19 in which said oily material is dioctylsebacate.

I 23. The steel surface of claim 19 in which an acceler ator is used to accelerate the coating of said phosphat ing agent on said surface.

24. The steel surface of claim 23 in which said accelerator is sodium nitrite or sodium nitrate.

25. The steel surface of claim 19 in which said acidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.

26. The steel surface of claim 19 in which said surface is uniformly coated with about 5 to lOO milligrams of said oily material per square meter of surface.

27. The steel surface of claim 19 in which said phosphating agent and said oily material are coated on said surface from an aqueous emulsion. l 

1. A STEEL SURFACE PER-TREATED TO PROVIDE SUPERIOR RUST PROTECTION, HIGH LUBRICITY AND DIRECT PAINTABILITY WITHOUT DEGREASING, SAID SURFACE HAVING A FIRST UNIFORM COATING OF UP TO 50 MILLIGRAMS OF PHOSPHATING AGENT PER SQUARE METER OF SURFACE AND A SECOND UNIFORM COATING OF AN OILY MATERIAL SELECTED FROM THE GROUP CONSISTING OF MINERAL OILS, VEGETABLE OILS, ANIMAL OILS AND EQUIVALENT SYNTHETIC OILS, SAID PHOSPHATING AGENT BEING COATED ON SAID SURFACE FROM AN ACIDIC AQUEOUS SOLUTION OF SAID PHOSPHATING AGENT SAID SECOND COATING BEING APPLIED SUBSEQUENT TO SAID FIRST COATING.
 2. The steel surface of claim 1 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.
 3. The steel surface of claim 2 in which said phosphorus oxy acid is orthophosphoric acid.
 4. The steel surface of claim 1 in which said oily material is dioctylsebacate.
 5. The steel surface of claim 1 in which an accelerator is used to accelerate the coating of said phosphating agent on said surface.
 6. The steel surface of claim 4 in which said accelerator is sodium nitrite or sodium nitrate.
 7. The steel surface of claim 1 in which said aCidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.
 8. The method of claim 1 in which said surface is uniformly coated with about 5 to 100 milligrams of said oily material per square meter of surface.
 9. The method of claim 1 in which said surface is uniformly coated with 0.01 to 50 milligrams of said phosphating agent per square meter of surface.
 10. A STEEL SURFACE PE-TREATED TO PROVIDE SUPERIOR RUST PROTECTION, HIGH LUBRICITY AND DIRECT PAINTABILITY WITHOUT DEGREASING, SAID SURFACE HAVING A UNIFORM COATING OF UP TO 50 MILLIGRAMS OF PHOSPHATING AGENT PER SQUARE METER OF SURFACE AND AT LEAST 150 MILLIGRAMS OF OILY MATERIAL PER SQUARE METER OF SURFACE, SAID PHOSPHATING AGENT AND SAID OILY MATERIAL BEING COATED ON SAID SURFACE SIMULTANEOUSLY, SAID PHOSPHATING AGENT BEING COATED ON SAID SURFACE FROM AN ACIDIC AQUEOUS SOLUTION OF SAID PHOSPHATING AGENT, SAID OILY MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF MINERAL OILS, VEGETABLE OILS, ANIMAL OILS AND EQUIVALENT SYNTHETIC OILS.
 11. The steel surface of claim 10 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.
 12. The steel surface of claim 11 in which said phosphorus oxy acid is orthophosphoric acid.
 13. The steel surface of claim 10 in which said oily material is dioctylsebacate.
 14. The steel surface of claim 10 in which an accelerator is used to accelerate the coating of said phosphating agent on said surface.
 15. The steel surface of claim 14 in which said accelerator is sodium nitrite or sodium nitrate.
 16. The steel surface of claim 10 in which said acidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.
 17. The steel surface of claim 10 in which said oily material and said phosphating agent are located on said surface from an aqueous emulsion.
 18. The steel surface of claim 10 in which said surface is uniformly coated with 0.01 to 50 milligrams of said phosphating agent per square meter of surface.
 19. A STEEL SURFACE PER-TREATED TO PROVIDE SUPERIOR RUST PROTECTION, HIGH LUBRICITY AND DIRECT PAINTABILITY WITHOUT DEGREASING, SAID SURFACE BEING COATED WITH A PHOSPHATING AGENT AND UP TO 150 MILLIGRAMS OF OILY MATERIAL PER SQUARE METER OF SURFACE, SAID PHOSPHATING AGENT AND SAID OILY MATERIAL BEING COATED ON SAID SURFACE SIMULTANEOUSLY, SAID PHOSPHATING AGENT BEING COATED ON SAID SURFACE FROM AN ACIDIC AQUEOUS SOLUTION OF SAID PHOSPHATING AGENT, SAID OILY MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF MINERAL OILS, VEGETABLE OILS, ANIMAL OILS AND EQUIVALENT SYNTHETIC OILS.
 20. The steel surface of claim 19 in which said acidic aqueous solution of said phosphating agent is an acidic aqueous solution of a phosphorus oxy acid or its salt.
 21. The steel surface of claim 20 in which said phosphorus oxy acid is orthophosphoric acid.
 22. The steel surface of claim 19 in which said oily material is dioctylsebacate.
 23. The steel surface of claim 19 in which an accelerator is used to accelerate the coating of said phosphating agent on said surface.
 24. The steel surface of claim 23 in which said accelerator is sodium nitrite or sodium nitrate.
 25. The steel surface of claim 19 in which said acidic aqueous solution of said phosphating agent contains about 0.01 to 1.0 percent by volume of said phosphating agent.
 26. The steel surface of claim 19 in which said surface is uniformly coated with about 5 to 100 milligrams of said oily material per square meter of surface.
 27. The steel surface of claim 19 in which said phosphating agent and said oily material are coated on said surface from an aqueous emulsion. 